Wildlife of the Week #1   Porcupine  -  Megan Edgar, Wagner Natural Area Society, May 9, 2018

Common name: North American porcupine, Common porcupine, Canadian porcupine

Scientific name: Erethizon dorsatum

Family: Erethizontidae

Porcupines are otherworldly animals, with spikes that grow from their backs, strong climbing skills, and who have a bad reputation to many dog owners. North American porcupines can be found in Wagner Natural Area and throughout Canada. Through my research I have learned that the porcupine is the second largest rodent in Alberta (Alberta Agriculture and Forestry 2005). Porcupines can measure up to 90 cm in length, weigh as much as 12 kg and can live up to 18 years in the wild. These long-living rodents are widely dispersed through the province, but typically near forest stands. Porcupines are a nocturnal species, primarily active throughout the night, and have poor eyesight, but their senses of hearing and smell are excellent. What I found surprising, and I am sure others would too, is that this species does not hibernate over the winter. Other identifying features of this animal are their thick tail and short powerful legs with long, curved claws. These claws make it easier for them to grasp and climb trees (Alberta Environment and Parks 2010). They tend to feed on green leaves of forbs, shrubs and trees in the summer. In the winter they feed on the inner bark (cambium), twigs and buds of trees.

    
Figure 1:Trunk damage caused by porcupine at Wagner Natural Area. 
Photo credit: Britney Blomquist

One of their unique features is their defence mechanism, which is what people typically tend to think of when they imagine the porcupine. Myself, and I’m sure others, have seen this defence mechanism in action when curious dogs approach a porcupine, only to have 30 quills stuck in their curious snouts.  On a porcupine’s body, it can have up to 30,000 fortified and barbed quills that are included in the composition of their coats (Alberta Agriculture and Forestry 2005). According to Alberta Environment and Parks (2010), and contrary to some beliefs, porcupines cannot throw their quills, rather they can embed their quills into a perceived threat with a speedy slap of their tails. Alas, knocking aside our preconceived ideas that we learned as children while watching cartoons where the quills of the porcupine fly out of their backs. Before the porcupine slaps their tail into a threat, they will communicate that they are feeling threatened by vocalizing, as well as displaying their quills and chattering their teeth together. In these situations it is important to back away slowly and respect the animal’s presence. Interestingly, these quills are hollow which reduces their body weight and adds to the buoyancy of the animal, which is useful when the porcupine occasionally swims.           

          Different from other rodent species, there is usually only one porcupine that is born to each female between mid-May through to July (Alberta Environment and Parks 2010). The young are precocial, meaning they are born in an advanced state of development and are able to feed themselves almost immediately. This characteristic is unique to the porcupine, as it is the only North American rodent to give birth to precocial young. According to the Edmonton and Area Land Trust website (2016), the baby porcupines, adorably known as porcupettes, should be left alone if a person were to find them on the ground. Though one may want to do the opposite of what this website advises, as is the good nature of humans to help baby animals, this is where the mother porcupine will leave her young while she naps in the trees, and will return at night to feed her young (so don’t fret!).

    
Figure 2: North American porcupine in tree.
Photo credit: Paul Bolstad.
www.bugwood.org

It takes only one jaunt around the Marl Pond Trail at the Wagner Natural Area to witness the moderate foraging that the North American porcupine presence has on the large white spruce trees (Picea glauca) near Post #8 and the Windfallen White Spruce area of the trail. If you look closely through the trees, you can see that one of them has been heavily foraged around the entire trunk, this is called girdling. Though the porcupine does have the capacity to girdle trees and ultimately cause mortality by feeding on the inner tree bark, buds, twigs and evergreen needles, it is important to keep in mind their significance (Edmonton and Area Land Trust 2016).  Porcupines help keep forests healthy by eating mistletoe, a parasitic plant that grows on many different tree species, as well as thinning out dense stands of saplings.

           

References:

Alberta Agriculture and Forestry. (2005). Control of Porcupine Damage. Retrieved from https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3470 [May 9, 2018].

 Alberta Environment and Parks. (2010). Common Porcupine (Erethizon dorsatum). Retrieved from http://aep.alberta.ca/fish-wildlife/wild-species/mammals/rabbits-rodents/porcupine.aspx [May 9, 2018].

 Edmonton and Area Land Trust. (2016). Porcupine. Retrieved from https://www.ealt.ca/species-spotlight-list/porcupine [May 9, 2018].